Sampling serial samplers

Serial samplers as part of a sampling system (plus winch, hydrowire, bottom weight) used from ships, optionally supplied with reversing thermometers, triggered by messengers ... 

A second strategy relies on parallel experimentation. In this case, the same experimental step is performed over n samples in n separated vessels at the same time. Robotic equipment such as automated liquid-handlers, multi-well reactors and auto-samplers for the analysis are used to perform the repetitive tasks in parallel. This automated equipment often works in a serial fashion as, for example, a liquid handler with a single dispensing syringe filling the wells of a microtiter plate, one after another. However, the chemical formation of the catalyst or the catalytic reaction are run at the same time, assuming that their rate is slow compared to the time needed to add all the components. The whole process appears parallel for the human user whose intervention is reduced. 

The focus of this chapter has been on the synthesis of new catalysts by parallel and combinatorial methods. Another aspect important to the development of new catalysts by these methods is the screening of these large libraries. We will not attempt to cover this topic comprehensively but do feel it is necessary to summarize some of the approaches that have been taken. Methods for screening libraries can be divided into both serial and parallel methods. Generally, the serial methods are adaptations of standard methods that allow for rapid individual analysis of each member of a library. Serial approaches for the analysis of libraries can be as simple as use of an auto sampler on a GC or HPLC system or as advanced as laser-induced resonance-enhanced multiphoton ionization of reaction products above the head-space of a catalyst (16) or microprobe sampling MS (63). The determination of en-antioselectivity in catalysis is a particular problem. Reetz et al. (64) reported the use of pseudoenantiomers and MS in the screening of enantioselective catalysis while Finn and co-workers (65) used diastereoselective derivatization followed by MS to measure ee. 

A specially modified sampler for Desaga expands the TLC-Applicator AS 30 into a fully automatic application system. The applicator control of the autosampler is performed by a serial interface, and it monitors the selection of sample containers, the delivery of the necessary amount of sample, and the rinsing processes. A second serial interface allows the application parameters to be documented using a printer or laboratory computer system. 

In addition to appropriate samplers, components of an optimum sampling system for trace element studies involve plastic (coated) wires , such as made of Kevlar, or plastic coated hydrowires, serial winches with plastic drums and plastic-coated bottom weights and messengers. 

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